Deposits - Summary of Total Earnings Credit and Referral Costs (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2026	Mar. 31, 2025
Deposit Liability [Line Items]
Deposits, Earnings Credit And Referral Costs	$ 214.3	$ 192.2
Interest income
Deposit Liability [Line Items]
Deposits, Earnings Credit And Referral Costs	48.7	58.1
Service charges and fees
Deposit Liability [Line Items]
Deposits, Earnings Credit And Referral Costs	8.3	4.2
Deposit costs
Deposit Liability [Line Items]
Deposits, Earnings Credit And Referral Costs	157.3	129.9
Other deposit related costs	$ 6.0	$ 6.9

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name Regulation S-K (SK)
-Number 229
-Section 1406
-Paragraph a
-Subparagraph (2)
-Publisher SEC

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name Regulation S-K (SK)
-Number 229
-Section 1406
-Paragraph a
-Subparagraph (1)
-Publisher SEC

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Name Regulation S-K (SK)
-Number 229
-Section 1406
-Paragraph a
-Subparagraph (5)
-Publisher SEC

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Name Regulation S-K (SK)
-Number 229
-Section 1406
-Paragraph c
-Publisher SEC

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Name Regulation S-K (SK)
-Number 229
-Section 1406
-Paragraph a
-Subparagraph (3)
-Publisher SEC

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Name Regulation S-K (SK)
-Number 229
-Section 1406
-Paragraph a
-Subparagraph (4)
-Publisher SEC

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